Balanced resiliency multiple-action one-piece diaphragm



Oct. 22, 1929. G. F. BORKMAN- 1,732,351

BALANCED RESILIENCY MULTIPLE ACTION ONE-PIECE DIAPHRAGM Filed March 51, 1926 Patented Oct. 22, 1 929 PATENT OFFICE GEORGE E. BORKMAN, OF SALT LAKE CITY, UTAH BIALANCED RESILIENCY MULTIPLE-ACTION ONE-PIECE DIAPHRAGM Application filed March 31, 1926. Serial No. 98,937.

This invention relates to a balanced resiliency multiple action one-piece diaphragm, for the production or reproduction of sound, and its principal objects are:

First. To provide a diaphragm which may be used for sending or receiving, that is, for use either with a microphone or with a telephone or radio receiver Second. To provide a diaphragm which shall have balanced resiliency, thereby avoidlng the necessity of the customary polarity selection when assembling and testing the instruments in Whichthe diaphragms are used.

Third. To obtain in a single diaphragm a high degree of tone variation, with equal fidelity to pitch Whether the tone vibrations are of high frequency or low frequency.

Fourth. To obtain in a thin sheet diaphragm the advantages sought by others in a heavy rim and light center construction,

these latter having been found to be costly and impractical, especially where attempts have been made to build up the diaphragms I of mica in laminated form.

Fifth. To confine the major effect of sound vibrations to the central portion of the diaphragm.

Sixth. To cause the light tone impulses to affect thecentral portion of the diaphragm and to automatically cause the stronger tone impulses to act upon the outer portion of the diaphragm when the center portion becomes overloaded.

Seventh. To obtain highquality of manufacture at a minimum cost.

Ei hth. To adapt thelconstruction of the diap ragm to modern methods of quantity production.

Ninth. To combine in an instrument with one diaphargm the efi'ects usually obtained only by two or more instruments playing at one time, in close proximity to each other in order to obtain the reproduction of high and low notes, either vocal or instrumental, thereby achieving a result which is being largely sought at this time by all persons interested in sound reproduction.

These objects are attained preferably by stamping -the diaphragms from thin sheet metals such as aluminum, and providing a series of corrugations concentric with the diaphragm, and in addition, a series of radial corrugations which may intersect the concentric corrugations. The radial corrugations are spaced equallyaround the center of the dia-' phragm, and extend inwardly, preferably from the circumference of the diaphragm, to an extent dependin upon the relation of the tone qualities to be liorne by the central portion of the diaphragm in comparison with the outer portion thereof.

The radial corrugations further, are formed in alternating relation to each other, that is to say one corrugation shall be concave when considered from one surface of the diation;

Fig. 2, a section on line 2 in Fig. 1; FFig. 3, a developed section on line 3 in Fig. a plan showing a modification; and

Fi 5, a section on line 5 in Fig. 4:.

Re erring to the drawing, the diaphra m 10 has the usual clamping margin 12 by WhlCll it is held in lace in its mounting. At the center of the iaphragm is the cup portion 14 which is preferably in the form of the hollow frustrum of a cone. Concentric with the frustrum are the corrugations 15 to 21, these corrugations being consecutively adjacent each. other and occupying the area between the base of the frustrum and the clamping margin 12. Extending radially across the corrugations 18 to 2l,are the convex corrugations 24 alternating with the concave corrugations 25, the terms convex and concave being used in this instance, relatively to the to surface of the diaphragm, as shown in F1 s. 1 and 3.

%he diaphragm 34 in Fig. 4, has the cup 26 and the convex radial corrugations 31 alternating with the concave radial corrugations 32.

The relative difierences in the shapes of the cups 14 and 26 and the differences in the arrangements of the concentric corrugations 15 to 21 and 27 to 30 represent the facility with which differences in tone pitches of various diaphragms may be effected.

The diaphragm represented in Fig. 1 is typical of the general arrangement for producing tones of low pitch, for the reason that the sound impulses would affect the diaphragm largely within the central portion thereof. On the other hand, the frustroconical cup represented in Fig. 4 having a much larger base than the cup 14 in Fig. 1, would bring the effect of the sound impulses nearer to the margin thereof.

By properly proportioning and arranging the cup and the concentric corrugations, and then by properly placing the radial corrugations, almost any desired tonal qualities can be provided for in a single diaphragm.

In ordinary diaphragms, that is those not having my alternating convex and concave radial corrugations, the tone action of the diaphragm when moved in one direction, is different from the tone action when the same diaphragm is moved in the opposite direction, this being probably due to an unavoidable difference in the two surface structures of any sheet of material.

I have found, as the result of many experiments, that the alternating arrangement of the radial corrugations as herein disclosed, overcomes this undesirable condition present in ordinary diaphragms, thus making unnecessary in my improved construction, the polarity selection of the diaphragm.

While a typical embodiment of this invention is herein shown and described, it should be clearly understood that all the detailed parts thereof, may or may not, appear in the preferred forms, and also, that the preferred forms may be varied from time to time, depending upon the circumstances and conditions governin and governed by, the development of t is invention and the arts to which it is incident, therefore the scope of this invention may be ascertained from the claims in which its spirit is generalized.

Having fully described my invention, what I claim is:

1. A diaphragm substantially circular in form and constructed of material of uniform thickness, said diaphragm comprising a centrally disposed cup portion, concentric corrugations surrounding the said cup portion in spaced relation to each other, and a p1u ralityof radial corrugations spaced apart from each other, the radial corrugations intersecting a predetermined number of the said concentric corrugations, and being alternately concave and convex relatively to each other.

2. A diaphragm having a seriesof radial corrugations formed therein in alternating convex and concave relation, and a second series of corrugations having individual member corrugations intersecting individual member corrugations of the said first series, transversely with respect to the plane of the diaphragm.

3. A diaphragm of substantially uniform thickness having a plurality of radial corrugations formed therein, the lengths and shapes of the said corrugations being similar to one another, but alternately concave and convex with respect to the plane of the diaphragm and a second series of corrugations having individual member corrugations intersecting individual member corrugations of the said first series, transversely with respect to the plane of the diaphragm.

4. A diaphragm having a plurality of corrugations formed therein, said plurality comprising an even number of corrugations, one-half of which are'concave and the other half convex, and a second series of corrugations having individual member corrugations intersecting individual member corrugations of the said first series, transversely with re spect to the plane of the diaphragm.

In testimony whereof I sign my name hereto.

GEORGE F. BORKMAN. 

